1. Field of Invention
This invention relates to lubricating oil compositions. More particularly, this invention relates to lubricating oils of high dispersancy-detergency and high alkalinity reserve for use as crankcase lubricant in marine and heavy duty diesel, such as railway diesel engines.
2. Description of the Prior Art
Heavy duty diesel engines require crankcase lubricant oils which are stabilized against oxidation, are non-corrosive to bearing materials including silver, and suspend combustion products which would lead to the formation of deposits in engines and formation of sludge and varnish on piston, cylinders, cylinder liners, and undercrown cavities. The diesel crankcase lubricant should prevent carbon deposition especially in the top ring piston groove. High alkalinity is required to neutralize acids formed during fuel combustion, and to reduce the frequency of oil changes. In addition, the crankcase lubricating oil for heavy duty diesel engines must be so formulated that silver, copper, and lead parts in the engine are not attacked either by the additives in the oil or by the dispersed neutralized decomposition products produced during extended engine operation. The present invention is directed to an new, unique combination of lubricant oil additives in a suitable base oil for heavy duty diesel engine crankcase lubrication. The diesel engine crankcase lubricant composition of this invention, when field tested in modern, high-speed, railway diesel freight engines, has demonstrated the ability to maintain a clean engine and provide increased alkalinity reserve in the used crankcase oil, while at the same time protecting lead, copper, and silver-surfaced parts in the engine. Compatibility of this oil with other current railway oils has been shown in bench and engine tests. Formulations of lubricating oil exist which give adequate protection to heavy duty diesel engines. A novel formulation of a lubricating oil has been discovered which gives superior dispersancy-detergency, and superior alkalinity reserve and protection of lead and silver parts in raileay diesel engines.
Thus, it is an object of the invention to produce a novel, improved lubricating oil. Another object of the invention is to produce a novel lubricating oil with increased alkalinity reserve. Sitll another object of the invention is to produce a novel lubricating oil which provides superior protection to lead, copper, and silver parts in railway engines. A further object of the invention is to produce a new lubricant oil which has a lower ash content than other railway oil formulations with equivalent alkalinity. Other objects of the invention are to produce an extended life railway diesel engine lubricant oil which controls engine deposits, provides protection against corrosive wear, especially with high-sulfur diesel fuels and maintains an adequate alkalinity reserve under severe operating conditions.